The 30-year-old singer-and-actor admits he "absolutely" smokes marijuana-laced cigarettes because he believes it helps him to switch off and relax more.

He said: "The only thing pot does for me is it gets me to stop thinking. Sometimes I have a brain that needs to be turned off. Some people are just better high."

Although Justin is comfortable smoking marijuana now, he admits he gave up for a year following his appearance on 'Punk'd' in 2003 - where Ashton Kutcher's team of pranksters pretended to be government agents seizing all his property because of unpaid taxes - after being so "stoned" he was completely taken in by the hoax.

He recalled to Playboy magazine: "I actually stopped smoking pot for nine to 10 months after that. I was so stoned.

"If you ask my friends, if they're honest, they would probably say that's the only way to get me as dizzy as I was."

Justin also blasted "cruel" internet commentators for mocking his former girlfriend Britney Spears and her dancing.

He said: "The internet is a cruel place. What a f**ked-up thing to do. In Britney's defence, if you pulled up a video I did from 2003, I couldn't do the s**t I did then either.

"I'd love to see the people who comment about Britney online say those things to her face, because they couldn't. But this thing that happens online bothers me - these anonymous commenters. People think they can say anything and it doesn't matter to people."